Abstract
Simulation of the rate of hydrogenolysis of propylene was performed by use of the REMEGH computer program based on the free radical chain mechanism proposed by A. Amano et al.29) and simplified by the authors3). The mechanism is described as follows;
C3H6_??_C3H5•+H• (1), (2)
H•+C3H6_??_H2+C3H5• (3), (4)
H•+C3H6→C2H4+•CH3 (5)
•CH3+H2→CH4+H• (6)
•CH3+C3H6_??_CH4+C3H5• (7), (8)
V=d[C2H4]/dt=k5[H•][C3H6]=k5(k1•k4/k2•k3)1/2[H2]1/2[C3H6] (9)
The observed rate was quantitatively delineated by the above network of the elementary reactions and the relewant rate constants found in literature2), 7), 8), 13) except the rate for reaction (5) which was computed in this work as 1.1×108 (l/mol•sec) at 998K (Table 1). This rate constant was in fairly good agreement with that estimated from Benson's method9) for bimolecular association step and RRKM model3), 10) for unimolecular decomposition of the association product-hot n-propyl radical (Fig. 3). Ethylene yield was calculated as a function of the rate constants of the elementary reactions (1), (2), (7), and the results are shown in Figs. 4-6. The plots of log v vs. log [C3H6] or log [H2] were obtained (Figs. 7, 8), and the reaction order with respect to [C3H6] or [H2] could be obtained from the slope. The dependence of overall rate on the elementary rate constants k1-k5 could be obtained by use of a similar method (Fig. 9). The results were in good agreement with the experimental. The overall rate equation (9) derived from the reaction mechanism based on the steady-state assumption was justified by the result of numerical computation. All of these findings strongly supported the validity of the free radical chain mechanism described above.
